Data on psychobiological stress reactivity in essential hypertension demonstrated physiological hyperreactivity to acute psychosocial stress in hypertensives as compared to normotensive controls in terms of sympathetic nervous system and hypothalamus-pituitary-adrenal axis activity, blood lipids, and coagulation activity. Moreover, we found lower perceived social support in hypertensives as compared to normotensives, with the highest physiological stress responses in hypertensives with low perceived social support.. In addition, the collaborating group of Prof. Heinrichs demonstrated that OT and social support interact to reduce neuroendocrine responses to stress in normotensive individuals. Given these findings and given the aforementioned hypothesized role for OT in physiological stress reactivity, particularly in hypertension, it seems promising to investigate the combined effects of OT and social support provision on physiological stress reactivity in essential hypertensives as compared to normotensives.